User interfaces on mobile computing devices encounter various problems such as sensitivity to price, size, storage space requirements, power consumption and user ease of interaction. Typically, mobile computing devices include a input tactile pad (or finger-screen contact) and separate discrete tactile push buttons.
Input pads are position indicating devices that utilize capacitive input sensing technology to control cursoring, scrolling, gesturing and the like on a display in an electronic device. Capacitive touch sensing technology is rooted in the understanding that when two electrically conductive objects come near each other, their electric fields interact to form a capacitor. For example, electrodes and a human finger or a stylus are conductive elements. When a user places their finger near an electrode, a capacitor forms between the finger and the electrode.
Conventional input pads include a first set of conductive traces or grid layer that runs in a first direction to form rows and a second set of conductive traces or grid layer that runs in a second direction orthogonal to the first direction to form columns. Along each of the sets of conductive traces includes a multiplex of capacitive sensors or electrodes. The number and spacing of electrodes along each of the sets of conductive traces depends on the desired resolution of sensing. An integrated circuit is coupled to the array of conductive traces and capacitive sensors and responds to changes in capacitance between capacitive sensors and between a sensor and virtual ground.
In general, conventional input pads having a multiplex of capacitive sensors on first and second sets of conductive traces (or grid layers) includes a top layer having a continuous surface. Any breaks, voids or isolated sections of the top layer of the input tactile pad prevents the capacitive sensing circuitry from making accurate capacitive readings to determine an accurate position for the display.
Merging an input pad and tactile push buttons on a mobile computing device can address the mobile device problems related to size. However, merging these two forms of input using conventional input pad technology can lead to increased problems regarding price, physical size requirements and complexity.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.